Conventional high-frequency broadband amplifiers with a feedback resistor between an output node and an input node exhibit significant gain variation over temperature. Minimal gain variation over temperature is desired to improve system performance of the amplifiers. However, simple temperature-dependent feedback resistors are difficult to create to compensate for the temperature variations of the amplifiers.
It would be desirable to implement a controlled transistor on-resistance with predefined temperature dependence.
The invention concerns an apparatus including a first circuit and a second circuit. The first circuit may be configured to generate (i) a variable current and (ii) a constant current. The variable current may be proportional to a temperature of the first circuit. The second circuit may be configured to present a resistance through a plurality of first transistors between two ports in response to both the variable current and the constant current. The resistance may have a predefined dependence on the temperature.